Comparison of a Modified Double Poling Ergometer for Cross Country Skiers with Disabilities

by Forbes, Scott Chapman

Abstract (Summary)

The purpose of this study was to compare physiological variables (i.e. oxygen consumption, blood lactate, heart rate, respiratory exchange ratio) during exercise on a double poling ergometer modified for sit skiers to a field test for the same skiers. Three male and four female athletes from the Canadian National / Developmental team (17-54 years of age, ranging in ability from a complete T7 spinal injury to cerebral palsy) completed a field test and a double poling ergometer protocol separated by at least 24 hours. Both protocols consisted of three maximal sets of skiing of three minutes duration per set separated by approximately one and a half minutes rest. A wireless metabolic system (Sensormedics, VmaxST or Cosmed, K4b2) and heart rate monitor were used to measure physiological responses during each test. Arterialized blood lactate was measured before and after each set and for 15 minutes post exercise. There were no significant differences between the field and ergometer tests for peak oxygen consumption (VO2 peak) (field=35±6 mL/kg/min vs. ergometer=33±7 mL/kg/min; p=0.491). However, significantly higher peak heart rate (field=173±5 bpm vs. ergometer=178±4 bpm; p=0.046) and respiratory exchange ratio (RER) (field=1.2±0.1 vs. ergometer=1.4±0.1; p=0.022) were found during the double poling ergometer protocol. There were no significant differences in blood lactate at baseline and after set one between protocols. However, a significantly higher lactate was found after set two (field=7±4 mmol/L vs. ergometer=12±5 mmol/L; p<0.001) and set three (field=8±3 mmol/L vs. ergometer=13±4 mmol/L; p=0.001) during the ergometer protocol compared to the field test. There were moderate correlations between the field and double poling ergometer for VO2 peak (r=0.79; p=0.035), and peak blood lactate (r=0.83; p=0.02). However, no correlations were found between protocols for peak heart rate (r=0.37; p=0.491) and RER (r=0.54; p=0.207). Results of this study suggest that the double poling ergometer is similar to a field test for evaluating VO2 peak in elite cross country sit skiing athletes; however, the ergometer test involves a higher heart rate and anaerobic component.